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Common question at Poligram Marmoraria is what to do and what not to do to clean the granite.
WHAT NOT TO DO:
Never use harsh cleaners such as steel sponges, acidic products like vinegar, lemon or anything with ammonia or bleach. Frequent use of these chemicals will weaken the sealant over time. Basically, the stronger the cleaner, the faster it will break the sealant.
WHAT TO DO:
Clean up spills as soon as you notice them. And use warm water, a mild soap or detergent, and a microfiber cloth towel to clean your granite countertop daily.